The present invention relates to valve structures for pneumatic tires and more particularly, relates to a valve structure that enables inflation of a pneumatic device in one simple operation to a predetermined pressure, it also prevents overpressure during inflation, regardless of the air supply pressure.
The use of tire valves for pneumatic tires is well known in the art and a substantially conventional structure has evolved, particularly for automobile pneumatic tires. Generally, the commercially used tire valves are one-way stem valves permitting the inflation of the tire while preventing the egress of air therefrom under normal conditions.
The importance of obtaining prescribed tire pressure is becoming increasingly recognized. Thus, it is well known that proper tire pressure is essential in order to achieve maximum safety and efficient operation of the vehicle. Thus, under- inflated tires substantially decrease gas mileage leading to increase pollution and increase wear on the tires. Over inflation, on the other hand, is equally undesirable, as it will lead to uneven tire wear and possible poor handling of the vehicle.
Many of the components of the modem vehicle are designed to operate together under predefined conditions, such components including the tires, springs, shocks, steering mechanism, etc. Improper tire inflation pressures can, as mentioned above, lead to excessive wear on such components as well as causing poor handling and/or braking.
In order to overcome the above, it has been proposed in the art to provide various tire pressure indicating devices for use with the conventional valve structure on the pneumatic tire. Such devices are shown, for example, in U.S. Pat. No. 3,650,150 to Eccles and U.S. Pat. No. 5,365,967 to Moore. While such devices do perform the function of providing a tire pressure indicator, it will be understood that the conditions under which a vehicle operates are severe and damage to mechanisms can occur. A problem associated with some known valve assemblies is the inherent cost of such assemblies. Many of the pressure indicating devices known in the prior art utilize a number of components and therefore are relatively expensive for the marketplace.
Drivers frequently ignore recommendations from tire manufacturers and road safety organizations to check pressure at least once a month, because of the hassle of performing the operation. The necessity of having a simple device not subject to malfunction and which prevents over inflation and which requires only one simple operation would be desirable.
With such a device, it would be possible for the vehicle owner simply to inflate the tires at regular intervals, while being assured that the proper pressure is attained.
A further advantage of such a type of structure is that the desired pressure will be set in conformity with the manufacturer's recommendations, thereby eliminating both the need for the vehicle owner to ascertain the desired pressure and also to prevent the intentional and/or inadvertent over inflation of the tire.